Ichnology and sedimentology of the early Permian deep-water deposits from the Lercara-Roccapalumba area (Western Sicily,Italy)

Summary Diverse and abundant trace fossils of the deep-waterNereites ichnofacies have been found in well-dated Early Permian deep-water turbidites (Lercara Formation) of western Sicily (Italy). Conodonts indicate a latest Artinskian to Cathedralian (late Early Permian) age. Microfossils (pelagic conodonts, albaillellid Radiolaria, paleopsychrospheric ostracods, foraminiferal associations dominated byBathysiphon), trace fossils (deep-bathyal to abyssalNereites ichnofacies) and sedimentologic data collectively indicate a deep-water environment for the Early Permian turbidites of the Lercara Formation. The dominance ofAgrichnium and of thePaleodictyon subichnogeneraSquamodictyon andMegadictyon suggests that this icnofauna is closely related in ichnotaxonomic composition to other late Paleozoic deep-water ichnofaunas. The occurrence ofAcanthorhaphe. Dendrotichnium andHelicoraphe, to date only reported from Cretaceous or Tertiary flysch deposits, suggests that the entire ichnofauna corresponds well to previously documented Silurian-Tertiary flysch ichnofaunas. Eight new ichnospecies and a new ichnosubgenus,Megadictyon, are described.     

Deep-sea ecosystem variability of the Aegean Sea during the past 22 kyr as revealed by Benthic Foraminifera

Specific responses of the regional deep-sea ecosystems to climatic and oceanographic processes during the last 22 kyr are revealed by benthic foraminiferal faunas from two cores in the northern and southern Aegean Sea. Under glacial boundary conditions, high-diversity benthic foraminiferal faunas and elevated benthic foraminiferal numbers indicate enhanced organic matter availability and well-ventilated deep-water masses in the whole Aegean Sea. The glacial termination is accompanied by significant fluctuations in productivity and deep-water ventilation. In the northern Aegean Sea, meltwater inflow from mountain glaciers during the Bølling/Allerød warm period resulted in a restriction of local deep-water formation, as mirrored by a dominance of bolivinids. During the deposition of sapropel S1, drops in benthic foraminiferal number and diversity are more significant in the southern Aegean Sea when compared to the north. This suggests the persistence of local deep-water formation in the northern Aegean Sea during S1 deposition. In addition, faunal fluctuations within S1 at both sites suggest the repeated influence of short-term cooling events on the re-ventilation and re-colonization of Aegean deep-sea ecosystems. During the middle and late Holocene, benthic foraminiferal faunas document the establishment of oligotrophic and well-ventilated conditions in the southern Aegean Sea. The corresponding faunas from the northern Aegean Sea reflect generally mesotrophic conditions and variable deep-water oxygenation. During the entire Holocene, the deep-sea ecosystems of this region responded very sensitively to short-term changes in humidity and temperature. These abrupt climate changes controlled the inflow of nutrients from rivers and the Black Sea and the formation of local deep-water masses.